Lipase inhibitors such as esterastin (see U.S. Pat. No. 4,189,438), tetrahydroesterastin (3,5-hydroxy-2hexadeca-7,10-dienoic 1,3-lactone), 3,5-dihydroxy-2-hexylhexadeca-7,10-dienoic 1,3-lactone, 3,5-di-hydroxy-2-hexylhexadecanoic 1,3-lactone, and the like, are well-known as lipase inhibitors and as pancreatic cholesterol esterase inhibitors. However, such lipase inhibitors are, inter alia, also substantially orally active as immunosuppressants (see U.S. Pat. No. 4,189,438 and U.S. Pat. No. 4,202,824), which can be a highly undesired side activity in a normal or immunosuppressed person.
A popular lipase inhibiting compound which is substantially non-absorbable is known as Orlistat ((2S,3S,5S)-5-[(S)-2-formamido4-methylvaleryloxy]-2-hexyl-3-hydroxy-hexade canoic 1,3 acid lactone, see U.S. Pat. No. 5,643,874). Orlistat has been used to inhibit lipases in the body and thereby prevent the absorption of dietary fat. At a 120 mg dose of Orlistat, taken before consuming a fat-containing meal (or up to one hour after eating such a meal), up to one-third of the fat eaten at a given meal will not be absorbed by the average person and utilized as dietary fat calories. The undigested fat passes directly through the digestive system as an oil and is ehininated from the bowel in its oily undigested form.
Certain polysaccharides are non-absorbable and some polysaccharides have the side benefit of reducing lipid absorption by the body. Defatted rice germ polysaccharides and sulfated polysaccharides are also lipase inhibitors. The super fiber Chitosan, which is a deacylated polysaccharide derived from shellfish chitan, has an ability to absorb fat and cholesterol, particularly in combination with vitamin C. Chitosan compositions may actually absorb up to 6 to 8 times its weight in fat and oils. While the polysaccharide from shellfish is similar to crude cellulose plant fiber, it has the ability to significantly bind fat in the digestive system as compared to plant fiber. Further, since polysaccharides, including those which do not preferentially bind oils over water, are not absorbed by the digestive systems of anmals such as humans, non-human primates, dogs and cats, there is no caloric value to such polysaccharides and they pass through the such digestive systems unabsorbed and substantially intact. Examples of non-absorbable polysaccharides are polysaccharides having a molecular weight of greater than 8 kDa such as dextrans, molecular microcrystalline cellulose, wheat bran, oat bran, defatted rice germ, alginic acid, pectin, amylopectin, chitin, crude cellulose, argar, chitosan and the like.
There is a need in the art for non-absorbable lipase inhibitors, as well as for improved antiadiposity compositions and methods which do not require an absolute low-fat diet in order to lower the absorption of dietary fat as calories.